Process and apparatus for pyrolysis of hydrocarbons



Feb. 11, 1958 s. P. ROBINSON PROCESS AND APPARATUS FOR PYROLYSIS OFHYDROCARBONS Filed March 19. 195e 2 sheetssneet 1 INVENTOR. s. P.ROBINSON f/ f f l l/ b ml/ n CMQ ATTORNEYS Feb. 11, 1958 s. P. ROBINSONPROCESS AND APPARATUS FOR PYROLYSIS QF HYDROCARBONS Filed March 19, 19562 Sheets-Sheet 2 .III

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BOLVAIVIB ATTORNEYS yUnited States PROCESS AND APPARATUS FOR PYROLYSIS FHY DROCARBONS Sam P. Robinson, La Porte, Tex., assignor to PhillipsPetroleum Company, a corporation of Delaware Application March 19, 1956,Serial No. 572,309

11 Claims. (Cl. 260-679) This invention relates to the conversion ofhydrocarbons at elevated temperatures. In one embodiment this inventionrelates to the production of acetylene. In one aspect this inventionrelates to the production of aromatic hydrocarbons. In another aspectthis invention relates to a process, and apparatus, in which a gas maybe quickly heated, maintained at a resulting elevated temperature for apredetermined time and then quickly quenched. In another aspect thisinvention relates to apparatus for use in the pyrolysis of a hydrocarbongas to form acetylenecontaining product and for the production ofaromatic hydrocarbons and associated products from the acetylene productthus formed. This application is a continuationin-part of my copendingapplication Serial No. 85,344, led April 4, 1949, now abandoned, whichis a continuation-in-part of Serial No. 58,892, filed November 8, 1948,now U. S. Patent A2,608,594 (1952).

As is well known to workers in the art, hydrocarbons may be converted toacetylene by a high-temperature heat treatment, such as passage throughan elec-tric arc, partial combustion at high temperatures, or the like.Temperatures in excess of 2000 F. are necessary to obtain good yields ofacetylene, although some acetylene may be formed at much lowertemperatures. It is also well known that at an appropriate temperature,say in the range of about 1000 to 1200*o F., acetylene polymerizesrapidly to benzene and other normally liquid aromatic hydrocarbons.Therefore, it is possible to convert a gaseous hydrocarbon to normallyliquid aromatic hydrocarbons by subjecting a gaseous hydrocarbon to a primary heat treatment, at high temperature, in which acetylene isformed, and then subjecting thevacetylene-containing gas product to asecondary heat treatment at a relatively low temperature, such as from1000 to 1200 F., as already mentioned.

However, in the temperature range of 1000 to 1200" F., the contact timerequired for formation of economically feasible yields of light aromatichydrocarbon product is so long as to promote various side reactionssuchas polymerization of acetylene product to form high molecular weightcyclic hydrocarbons, and rehydrogenation of acetylene product to ethane.Under such conditions, high and selective yields of light aromatichydrocarbons Iare not obtained. `In the past, this has been the caseeven to a larger extent when operating at temperatures higher than 1000to 1200 vF. due to concomitantly increased carbon and polymer formation,resulting in even lower yields of desired-product.

This invention is concernedwitha process and'apparatus for the pyrolysisof hydrocarbons to form pyrolysis-product rich in acetylene, and for theproduction, when-desired, of light aromatic hydrocarbons together withrelatively minor amounts of dioleiin hydrocarbons and heavier aromaticsfrom the acetylene-containing pyrolysis product.

An object of this invention is to provide process and apparatus forconversion `of hydrocarbons.

Another. object ,ofthis invention is to provide apparatus `for thepyrolysis of hydrocarbons to acetylene.'

`carbon materials from the initial pyrolysis product.

Another object is to provide apparatus for the pyrolysis of hydrocarbonsto form pyrolysis product rich in acetylene and for the production oflight aromatic hydrocarbons together with relatively minor amounts ofdiolen hydrocarbons and heavier aromatics from the acetylenecontainingpyrolysis product.

Another object is to provide a hydrocarbon pyrolysis process for themanufacture of acetylene.

Another object is to provide apparatus for quickly heating a hydrocarbongas to a predetermined elevated temfor a predetermined time and thenquickly reducing said temperature to a predetermined lower temperaturelevel.

Another object is to provide apparatus for quickly heating a hydrocarbongas to a requisite elevated temperature for forming acetylene-containingproduct by pyrolysis, maintaining the pyrolysis temperature level forthe requisite contact time and then quickly reducing the temperature ofthe resulting pyrolysis product mixture to a lower temperature level atwhich acetylenev and oletns contained in the pyrolysis product are notundesirably further reacted.

It is still another object to provide a two-stage process for themanufacture of aromatic hydrocarbons wherein an acetylene-containing gasproduct is formed in a iirst stage, and is then vconverted in a secondstage to light aromatic hydrocarbons.

Another object is to provide apparatus and process for utilization ofytemperatures higher than those employed heretofore in the manufacture ofaromatic hydrocarbons ice ' from an lacetylene'-containing gas.

Other objects will be apparent, to one skilled inthe art, from theaccompanying discussion and disclosure.

In accordance with a broad embodiment of this invention, process andapparatus are provided for pyrolyzing `a hydrocarbon gas to formacetylene-rich pyrolysis product, and for forming aromatic hydrocarbonstogether with relatively minor amounts of dioleiins and other hydro- Invarious applications of my invention it is sometimes desired to dispensewith any further reaction of acetylenecontaining product to formaromatic hydrocarbons, and instead, to recover valuable pyrolysisproducts, particularly acetylene and ethylene. Obviously, a part of thepyrolysis product can be utilized in a subsequent aromatic hydrocarbonforming step, and a part recovered prior to any furtherreaction, andutilized elsewhere.

In the practice of one embodiment of my invention, hydrocarbon pyrolysisof the type discussed above, and

reaction of product of the pyrolysis to aromatic hydroconnectedco-axially at its upstream end with the smaller cylinder chamber; asecond Venturi tube connected at its upstream end with the downstreamportion of the irst Venturi tube, preferably angularly, generally havingits longitudinal axis at substantially a right angle to that of thefirst Venturi tube; an auxiliary'reaction chamber `connected to thedownstream end of the second Venturi tube; inlet-means in the combustionchamber positioned 4in Aclose proximity to the burner end for admittinga tempering uid into the combustion chamber in a direction tangent toits interior cylindrical side wall, hydrocarbon inlet means intermediatethe combustion chamber and the iirst said Venturi tube for admittinghydrocarbon gas into the the mixing throat of the second Venturitube foradmitting quench fluidr into admixture with hot pyrolysis product.

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When the Venturi tubes are disposed at substantially a A right angle,the quench inlet is co-axially disposed with respect to the secondVenturi tube. Hydrocarbon gases introduced intothe apparatus arepreferably preheated, and this is advantageously done in a pebble heaterapparatus of the type generally known in the art.

Pebble heater apparatus referred to hereinabove usually comprises aseries of substantially vertically-extending zones, often in verticalalignment with each other. Usually two such zones are employed and areconnected by a relatively narrow connecting zone, or throat. The top orupper zone is commonly referred to as` the pebble heating chamber andthe lower zone as the gas reaction or gas heating chamber. A combustionZone, or cham ber, is positioned adjacent or in close proximity to thesides of the lower portion of the heating chamber. Combustion gas from acombustion chamber is passed through the mass of pebbles in the pebbleheating chamber. A contiguous mass of particulate contact material,often referred to as pebbles, fills the pebble heating zone, theinterconnecting zone or throat, and the gas reaction or heating Zone,and flows downwardly through these zones by gravity. Pebbles aredischarged from the bottom of the gas reaction zone at a controlledrate, and returned, usually by elevating means, to the inlet in theupper portion of the pebble heating Zone. A contiguous moving pebblemass thereby lls the pebble heating zone, gas heating zone, and theinterconnecting zone, or throat, at all times.

The term pebble as used in this specification denotes any refractorymaterial in fluent form, size, and strength, which will flow readily bygravity through the various chambers of a pebble heater apparatus.Pebbles are, preferably, substantially spherical and are about 1&2 inchto 1 inch in diameter, the preferred range being about 11/4 inch to 1/2inch.

Hydrocarbon gas to be converted to acetylene-rich pyrolysis product ispreferably preheated in a gas reaction chamber of a pebble heaterlapparatus of the type above discussed, to a temperature usually belowthat at which substantial hydrocarbon cracking takes place, which isusually below from 2000 to 2200" F. at a level dependent upon thespecific hydrocarbon being heated. In any case, it is usually desiredthat the amount of hydrocarbon cracking be not greater than percent.Hydrogen or hydrogen-rich fuel gas is burned with oxygen, and hot gasesformed from the combustion, pass axially through the centrallongitudinal portion of the combustion chamber. It is preferredgenerally to burn approximately stoichiometric proportions of hydrogenand oxygen, and under such conditions the ame temperature is from about4500 to about 5300 F. and is preferably from about 5000 to about 5300 F.Such temperatures are higher than those at which known present dayrefractory fabricating materials are economically utilized. Accordingly,a tempering gas, preferably steam or hydrogen, is introduced into thecombustion chamber through at least one tangential inlet in closeproximity to its burner and, in an amount to absorb heat from thecombustion gas and thereby to temper same to `a temperature of about4200 F. or below. Tempering gas, thus tangentially added follows aninitial inward spiral path in the cornbustion chamber and then moveshelically downstream, from the burner end, adjacent the chamber wall.The helically moving tempering gas forms a protective blanket adjacentthe combustion chamber walls, by virtue -of which, the walls areprotected from the peak oxygenhydrogen combustion temperatures, andabsorbs heat from the axially `fiowing combustion gas so that theoverall combustion gas temperature is reduced from about 5000 F. to 4200F. or less, .as discussed above. Furthermore, the helically moving gasimparts a swirling motion to the hot axially moving combustion gas.Heated hydrocarbon gas is withdrawn from the gas heating cham- 4 ber ofthe pebble heater apparatus, and injected, preferably in a radialdirection, into admixture with the axially moving, swirling, hotcombustion gas. Operating in this manner a highly efficient mixing ofhydrocarbon gas and axially moving combustion gas takes place. The hotcombustion gas thus contacted with the preheated but relatively coolhydrocarbon gas, transfers the necessary amount of heat to thehydrocarbon gas to elevate its temperature to a predetermined valuesuitable for its pyrolysis to form acetylene-rich hydrocarbon product.Mixing of hydrocarbon-combustion gas is nearly compiere upon initialcontact of these gases and the pyrolysis reaction fluid, usually steamor water.

is thus initiated. However, in order to effect further and completemixture of these gases in a very short time the admixture is passed intoa first Venturi tube of selected dimensions in which mixing of thehydrocarbon and combustion gas is completed. This final mixing takesplace as the gaseous mixture passes through the constrictedmost portionof the Venturi tube at which point the linear velocity is acceleratedand a great amount of additional turbulence is set up, whereby mixing iscomplete at the predetermined temperature level. Pyrolysis of thehydrocarbon components to the desired extent in the completely uniformlymixed combustion gas-hydrocarbon mixture is obtained by the time thegases pass from the Venturi tube exit throat. The length and angle ofthe Venturi tube mixing throat, the diameter of the constricted-mostportion and the length and angle of the exit throat of the Venturi tubeare selected in order to provide not only complete mixing, but also toretain the pyrolysis reactants for the necessary contact time so thatthe exit owing gas mixture from the Venturi tube is pyrolyzed to formacetylene in a maximum yield. In order to prevent overreacting of thepyrolysis mixture at the desired temperature level it is necessary toquickly terminate the pyrolysis at the end of the requisite Contacttime. This is done by quickly quenching the pyrolysis reaction mixtureas it ows from the exit throat of the Venturi tube. It is necessary thatmixing of quenching uid and hot gases be effected eiciently, quickly andcompletely. The exit flow of gases from the Venturi tube isadvantageously turned sharply, e. g. at about a right angle into asecond Venturi tube and at the same time admixed with quenching iluidintroduced at a point in the turn of the gas ow in a direction coaxialwith respect to the second Venturi tube, through the quench fluid inlet.Mixing of the quench uid and pyrolysis product gas is effected almostcom- Apletely as a result of a great amount of turbulence which is setup at the point of turn in the gas flow and by virtue of the injectioninto that zone `of turbulence, of the quench Quick and complete mixingof the quench iuid and pyrolysis product is effected by passing theresulting admixture through the second Venturi tube wherein the linearvelocity of these gases is accelerated and an additional gas turbulenceis set up and a uniformly quenched mixture is provided at the requiredlower temperature. Effluent quenched pyrolysis product, rich inacetylene, can then be recovered without further reacting same, or canbe passed into an auxiliary reactor or soaking-chamber where it may beconverted to aromatic hydrocarbons and other product. It is to beunderstood that diverting the direction of iiow of hot pyrolysis productmay be dispensed with, if desired. In

'- such instances, however, mixing of quench luid and hot product gas iseffected less efficiently, and less close control over desired reactingconditions is obtained.

The accompanying diagrammatic drawing illustrates a preferred form ofapparatus and a preferred process of my invention. It is to beunderstood that various moditaken oriA the line 2--2 of Figure 1. Figure3'1 a' dia*- gr'ammatic flowr sheet embodying ther apparatusillustratedin Figures 1 and 2, together with other `apparatus used in practicing apreferred embodiment of the process of this invention. 1 n

Referring now to Figure l, burner assembly 53 comprises conduit inlets44 and 51 arranged to respectively admit oxygen and hydrogen separatelyand axially for mixing in mixing throat 54, and burning at the tipdownstream from flame arrestor 58. Water inlet 57 and water outlet 59provide circulation of water through water jacket 56. Elongatedcylindrical combustion chamber 62, open at both ends, is connected atone end with burner assembly S3 to axially receive hot combustion gasfrom hydrogen-oxygen burning adjacent flame arrestor 58, and isco-axially connected at its Iother end with elongated cylindricalchamber 63, open at both ends, and having a smaller diameter than thatof chamber 62. Chamber 63 is co-axially connected yat itsA other end, i.e., its down'- stream end, with the upstream portion,-or mixing throat,of Venturi tube 64. L-shaped cylindrical connecting con.- duit 67connects Venturi tube 64 with a second Venturi tube 69 and is connectedco-axially at its upstream end 66 with the exit throat of Venturi tube64, and is connected co-axially at its downream end 68 with the mixingthroat of Venturi tube 69. Upstream portion 66 of connecting conduit 67may be of any desired length in order to provide for any desiredextension of contact time of the pyrolysis reaction ordinarilysubstantially completed in Venturi tube 64. Upstream member 66 may be ofminimum length to provide the necessary connecting length betweenVenturi tube 64 and the point of contact of pyrolysis product withquenching fluid. Similarly, the lower portion 68 of quenching chamber 67may be of any desired length to insure the proper amount ofl time formixing of quench uid with pyrolysis product gas. I have found that bydiverting the flow of gases about 90 the additional amount of turbulenceset up is so great as to require a lower portion 68 of minimum length.Except for the fact that lower portion 68 of connecting conduit 67provides a suitable means for connecting the two Venturi tubes as abovedescribed, the amount of quenching necessary would be effected in themixing throat'of Venturi tube 69 and completed in Venturi 69 to providea uniformly quenched pyrolysis product mixture having a temperature ata'predetermined level. Auxiliary reaction chamber 76 may be any suitablechamber for maintaining the exit flowing quenched pyrolysis productmixture from Venturi tube 69 in a desired temperature range for apredetermined contact time to convert unsaturated compounds therein,particularly ethylene and acetylene to aromatic hydrocarbon product.Chamber 76 is optionally utilized, and when so employed, is connectedwith the exit throat of Venturi tube 69 at its conduit inlet 73,preferably axially disposed with respect to Venturi tube 69. Gas outletconduit 70 and liquid outlet conduit 75 are located at the lower portionof chamber 76. Hydrocarbon inlet 36 is disposed to admit hydrocarbongas, to chamber 63, preferably radially. However, hydrocarbon gas may beintroduced to chamber 63, from line 36, in any direction, if desired.Quench fluid inlet 71 is disposed to admit quenching fluid, usuallywater or steam, into connecting conduit 67 in a direction coaxial withrespect to lower portion 68 of conduit 67 and Venturi tube 69. Inlets 61are disposed to admit tempering gas, preferably hydrogen or steam, intocombustion chamber 62 at points in close proximity to its burner end, ina direction tangent to its inner cylindrical wall and preferably withthe predominating component of motion perpendicularV to a planecontaining the longitudinal axis of chamber- 62. Inlets 61 arepositionedinclose-proximity to the burner end of chamber' 62 so astointroduce a-prol.tective' and tempering' gaslayer' intofchamber 62tocver its entire'interiorr wall surface. Inlets 61 are furtherillustratd in Figure 2.

The entirev apparatus above described is necessarily fabricated ofselected refractory materials. Obviously a wide selection can be made,by one skilled in the' art, from the various types of refractorymaterials" available on the open market; a However, at the hightemperatures already mentioned herein I generally prefer insulatingrefractories of the type illustrated in Figure 1 wherein liner 101 is avery highly abrasion-resistant, stabilized zirconia, liner 102 ofVenturi tubes 64 and 69 is a 99 percent alumina having strongabrasive-resistant properties, above about 3100 F. Layer 103 is a 3000F. insulating fire brick. Layer 104 is a 2600 F. insulating fire brick,layer 105 is a 2000 F. insulating fire brick and layer 106 is a magnesiainsulating material. The insulating materials represented herein aretypical of those from which suitable insulating materials may beselected. Obviously, other specific insulating materials may be selectedby one skilled in the art in order to more closely meet the specificrequirements of an individual set of conditions employed. n Y

With respect to Figure 2, tangential inlets 61 of Figure l are shown insectional view taken along line 2-2 of Figure l. Gas introduced throughconduits 61 enters chamber 62 tangentially, as already described. Insome instances of operation, one tangential inlet is suicient. However,it is within the scope of this invention to employ a plurality of suchinlets, preferably disposed equidistant about the periphery of chamber62. However, inlets 61 may be disposed at various selected points, asdesired.

I have found that although mixing of hydrocarbon and combustion gasesmay be effected in the apparatus' of this invention to a high degreewithout the use of Venturi tubes,` the mixing is not complete in theshort allotted time for forming acetylene product, but is quickly andcompletely effected Within such a short time, with the aid of'theVenturi tubes above discussed. The importance of quick and completemixing of gases in any process for acetylene production by pyrolysis ofhydrocarbons is well known. In order to prevent under-reacting and/oroverreacting during the pyrolysis, temperatures well above 2000 F. arerequired together with extremely short contact times as4 discussedhereafter. It is for such applications that the apparatus of thisinvention isV especially suitable. The minimum linear velocity of gasesin Venturi tubes 64 and 69 is about 200 feet per second and is greatlyaccelerated at the constricted-most portion. Such gas velocities causethe turbulence to provide perfect and final mixing in the allotted time,in each Venturi tube. The ex-it throat of Venturi tube 64 is designedforA maximum pressure head recovery, and for this purpose may generallyforman angleof about one-third that of the Venturi tube inlet throat,with the longitudinal axis of the exit throat about three times thelength of the longitudinal axis of the inlet throat. The selecteddimensions of Venturi tube 69 are of course dependent on the amount ofquenching fluid introduced from quenching fluid inlet 71. However, inorder to effect a quick and final mixing of quench fluid with pyrolysisproduct, the angle of the exit throat about twice the length of thelongitudinal'axis of the inlet throat and the longitudinal axis of theoutlet throat about twice the length of the longiudinal axis of the'inlet throat. It is to be understood that the specific dimensions to beutilized can be selected over a broad range by one skilled in the art inconsideration of the maximum pressure head recovery sought, and requiredlinear velocity of gases through the Venturi tubes.

With respect to Figure 3, I have illustrated by means of a diagrammaticflow sheet a preferred process of my invention embodying the'a'pparatusillustrated in Figures l and 2, together with a pebble' heaterVapparatus, and auxiliary apparatus for product separation,` recovery,and the like.l Referring then to' Figure 3, pebble'heating'zone c '7 andgas heating zone 11 are insulated chambers, each containing a contiguousmass of pebbles 12 and connected by a heat insulated conduit, formingpebble throat -13. Conduits 14 and 16 serve as pebble inlet and outletfor chambers 10 and 11 respectively. Star valve (or other type of pebblefeeder) 17 regulates the rate of ow of pebble mass 12, through chamber10, throat 13 and chamber 11, and feeds pebbles flowing from the bottomof chamber 11 into bucket elevator 18 for delivery into pebble inlet 14and on into chamber 10. Combustion chamber 19 is positioned subjacentpebble heating chamber 10. Chambers 10 and 19 are separated by perforatesupport 21 through which combustion gas formed in chamber 19 ascends topass in direct heat exchange relation with pebble mass 12 in chamber 10.Fuel gas, usually natural gas, from line 22, and/ or hydrogen recyclegas from lines 23 and 24, described herebelow, is introduced throughline 26 and mixed with oxygen or air from line 27 to form a combustionmixture in line 28 which is burned in combustion zone 19. Hot combustiongas formed in zone 19 ascends through perforate support 21 at atemperature in the range of 2200 to 3500 F. The temperature of thepebbles leaving zone 10, i. e., entering zone 11, is from 1800 to 2800"F. and may be controlled to higher or lower levels by regulating theproportion of oxygen introduced through line 27, the proportion ofhydrogen-rich gas introduced from lines 23 and 24, and by regulation ofthe rate of pebble llow through chamber 10. Pebble temperatures may belowered by introducing an inert gas diluent to the combustion chamber toeffect reduction in flame temperature. Combustion gas in zone 10 ispassed as effluent from zone 1t) through line 29 to further utilizationnot shown. Methane feed stock, often natural gas is introduced throughline 32 into the lower portion of gas heating chamber 11, entering at apoint below perforate gas distribution plate 33, -and is passedtherethrough in direct heat exchange relation with pebbles previouslyheated in zone 10, and is heated to a temperature within the range of1800 to 2400" F., a more preferable temperature range being from 1900 to2200" F. The extent of any hydrocarbon cracking in Zone 11 is limited byemploying a sufficiently short contact time, generally less than onesecond. I find, usually, that I can tolerate as much as percent crackingwhen preheating methane Yin this manner, and I prefer in any case tolimit the extent lof cracking by minimizing the heating time. Pressureconditions in the pebble heater apparatus are preferably atmospheric ornearly so. Pressures from 2 to 6 p. s. i. g. are preferred, althoughpressures as high as p. s. i. g. may be employed when desired. Hydrogenrecycle gas from lines 3S and 39 is preheated in preheater 41 to atemperature usually within the range of 500 to 1200 F., and passedthrough lines 42 to 51 into line 43 wherein it is mixed with commercialgrade oxygen, i. e., from 90 to 95 percent or higher purity, or anysuitable oxygenrich combustion supporting gas from line 44, initiallypassed from line 46, preheated in preheater 47 and passed into line 44through line 43, In some cases preheating of hydrogen recycle gas and/oroxygen is unnecessary, and in any such case hydrogen-recycle gas can bepassed directly from line 3S to line 43 through lines 49, 50 and 51, andoxygen can be passed directly from line 46 to line 43 through lines 52and t. Hydrogen and oxygen in line 43 are present preferably instoichiometric proportions for complete burning, although an excess ofhydro gen may be advantageously employed. Hydrogen-'oxygen gas from line43 is passed into water jacketed burner as sembly 53 and burned.Hydrogen-oxygen combustion gas formed by burning in burner 53 is passedaxially into the central longitudinal portion of combustion chamber 62at a temperature usually within therange of 5000 to 5300 F. If desired,a stoichiometric excess of hydrogen can be introduced into burnerassembly 53. In view of the fact that insulating rcfrac.ory materials inpresent day commercial use are uneconomically applied at such elevatedtemperatures, the refractory walls ofcombustion chamber 62 must beprotected from such extreme temperatures and the combustion gastemperature must be reduced, i. e., tempering to below about 4200" F.Both these steps are accomplished in cylindrical combustion zone 62.This is done by injecting steam, although hydrogen from lines 20 and 49may be advantageously employed, through lines 61 tangentially intocylindrical `chamber 62 through a single inlet or through a plurality ofsuch inlets in the burner end of chamber 62. Steam tempering gas thusintroduced forms a helically moving protective gas blanket as alreadydescribed. In this manner steam thus tangentially introduced absorbsheat from the hot combustion gas moving through the central longitudinalportion of chamber 62 while simultaneously forming a relatively Acoolprotective gas blanket adjacent the cylindrical inner wall of chamber 62during the tempering. Furthermore, the helically moving steam in chamber62 imparts a rapid swirling motion to the axially moving hot combustiongas.

Eilluent heated hydrocarbon gas, at an elevated temperature but not ashot as combustion gas in zone 62, is withdrawn from heating chamber 11through line 34 and passed through line 36, radially into cylindricalchamber 63 where it initially contacts, and is rapidly intermixed with,the swirling hotter combustion gases, and is very rapidly furtherheated. The rapid swirling motion of hot combustion gas, together withthe radial introduction of hydrocarbon gas into adrnixture therewith,provide for a maximum amount of turbulence and concomitantly a highdegree of hydrocarbon and combustion gas mixing. The resulting turbulentadmixture in chamber 63 is then passed into Venturi tube 64 at aninitial linear velocity not less than 200 feet per second, andpreferably higher. The upper limit of linear gas velocity in Venturitube 64 is determined by the abrasion resistant properties of refractoryfabricating', materials which limit is usually from 300 to 500 feet persecond. Venturi tube 64 is of sufficient length to provide for acompletion therein of hydrocarbon-combusti-on gas mixing and pyrolysisof hydrocarbons to acetylene-rich pyrolysis product. I have found thatthe time-temperature relationship necessary for the acetylene-formingreaction to be completed in Venturi tube 64 can be obtained when thelength of the exit throat is about three times that of the inlet throat.Pyrolysis gas product passed from Venturi tube 64 is quenched inquenching zone 67 in direct heat exchange relation with steam introducedinto zone 67 through inlet 71.

The temperature of the gas mixture passing into venturi 64 is regulatedby the temperature of the preheated gas from line 36 and the temperatureof the tempered combustion gas from chamber 62 and is in the limits of2400 to 3500 F., although a more preferable temperature is from 2600 to3000 F. The acetylene-forming pyrolysis reaction 1s initiated at thepoint of hydrocarbon-combustion gas contact. However, it is only aftercomplete and ecient mixing of hydrocarbon with hot combustion gas thatthe acetylene-forming reaction is c-ompleted. The overallacetylene-forming reaction takes place at a temperature in the rangeabove discussed, at a reaction time within the limits of 0.001 to 0.05second, the larger proportion of which takes place in Venturi tube 64.

Gaseous pyrolysis product is passed from Venturi tube 64 into connectingconduit 67 wherein its direction of flow is turned by about while at thesame time steam is introduced as a quench. A high degree of turbulenceis set up in zone 67 as the result of diverting the direction of flow ofgases, and it is into this highly turbulent mixture that quench steam orother iluid is introduced. The steam is added in an axial direction withrespect to Venturi tube 69, further discussed herebelow. The amount ofquenching fluid introduced through line 7l is obviously dependent uponthe amount of quenching needed, i. e., as to whether or notVvacetylene-containing asegura pyrolysis product is to be reacted furtherto form an aromatic-containing hydrocarbon product discussed more fullyhereafter, or free acetylene is` to be recovered for utilizationelsewhere. In the latter case water may be advantageously used toproduce faster cooling to a lower temperature. In any event, theresulting pyrolysis product admixture in zone 67 is passed into andthrough Venturi tube 69 wherein inal and complete mixing of quenchingfluid and pyrolysis product is eifected. Effluent quenched gas fromVenturi 69 is passed through lines 72 and 73 to auxiliary reactionchamber 76, or withdrawn through lines 72 and 74 and passed toseparation means 65 for separation and recovery of selected `productfractions. Separation zone 65 comprises various types of` well-knownproduct recovery equipment, not individually illustrated, especiallysuitable for recovering selected fractions from the material admittedfrom line 74, such as distillation, solvent extraction, absorption,settling storage, and the like. Selected product fractions separated inzone 65 include light gases (e. g. H2), acetylene, ethylene, and otherlight oleiins, or dioletns', together with residual carbonaceousby-product and water which are withdrawn respectively from zone 65through lines 75A, 70, 75, 80, 85, and 90. In the latter case eiuent gasfrom Venturi tube 69 is quenched to a temperature below that at whichacetylene and/or ethylene in the pyrolysis product further reactsappreciably to form polymer or to form carbon and hydrogen, whichtemperature is preferably below about 500 F.

However, I often prefer to pass the quenched pyrolysis product from'Venturi tube 69 to aromatics-forming chamber 76 for the conversion ofunsaturated pyrolysis product, particularly the acetylene and ethylenecomponents, to an aromatic hydrocarbon-containing product. Whenoperating in this manner, the amount of quenching steam introducedthrough line 71 is regulated to cool the pyrolysis product to anaromatics-forming temperature within the range of 1800 to 2300 F.

In aromatics-forming chamber 76, pyrolysis product from Venturi tube 69is maintained at its existing temperature (1800 to 2300 F.) for aduration of fro'r'n 0.05 to 5.0 seconds to form predominantly lightaromatic hydrocarbons, particularly benzene and toluene together withrelatively sm-all amounts of diolelin hydrocarbons and heavier aromatichydrocarbons formed as by-product. I prefer usually to quenchacetylene-containing pyrolysis product in z one 67 so that gases enterchamber76 at a temperature in a preferred range of' 1900 to 2200?y F.,and under such conditions a contact time within the limits of 0.2 to 3.0seconds may be selected.

Eluent from zone 76 is passed through line 77 and quenched to atemperature in the rangel of about 400 to 800 F. by admixtureV in line79 with; water sprayy introduced` through line 78. Theresultingadi'nixture is passed through' lines 81 and 82 to water quench tower 83wherein it is contacted countercurrently with water introduced throughline 84 andv cooled to a temperature usually within the range of 100 to200 F. If desired, material in line 79 may rst be passed through line86, cooler 87, and; line 88 to line 82, with or Without water introducedthrough line 78. Water may be drained from zone 83 through line 89, andany heavy by-product oils' removed through line 91". Product-containinggasl is passedl from zone 832 through line 92 to an absorber-strippersystem, preferably of the conventional type employing a mineral sealoilabsorbent. Material in line 92 is introduced to absorber 9`3aud passedtherein countercurrently in relation to down-flowing fresh and/ orstripped mineral seal oil introduced throughl line 110. Hydrogen-richgas isA passed from an upper portion of absorber 93 through line19"4'for combustion in zone 19 and/or burner 53; Anyl excessi recyclev gas`in line 94v may be withdrawnthrogh line 96. Enriched absorber oil ispassed through the lower portion of zone' 93'through line 97 andintroduced linto stripper 98 maintained under distillation conditionswhereby 'the rich' eil is heated and absorbed materials are liberated asvapors. Vapoized material is passed through line 107 from stripper 98 toproduct separation means 108 comprising coolers, separators,distillation equipment, storage tanks and the like not individuallyillustrated, which can be used to eiect a separation of various selectedproduct fractions. Lean absorber oil is passed from the lowerportion ofstripper 98 through lines 99 and 110 to absorber 93:. Fresh absorber oilcan be introduced to theabsorber system through line 111. Selectedproduct fractions separated in zone-108 include ybenzene withdrawnthrough line 112, toluene withdrawn through line 113., cyclopentadieneand other diolens withdrawn vthrough line 114, and a fraction containinglight aromatic hydrocarbons such as styrene, methylstyrene, and Xylenes,withdrawn through line 116. Arelatively heavy fraction of aromaticscomprising naphthalene, anthracene and other, heavier aromatics and/ ortars iswithdrawn through line 117.

During the non-process periods or when starting up, natural gas isintroduced into the water cooled burner through lines 35, t9 and 50 andburned with oxygen, and after pyrolysis is under way, the natural gasfeed to the burner is replaced with the recycle hydrogen stream. Freshhydrogen may be introduced into the burner system through line 30,.whenV desired.

Frconvenience and clarity certain apparatus such as pumps, surge tanks,accumulators, valves, etc. have not been shown in the drawing. Obviouslysuch modifications of the present invention may be practiced withoutdeparting from the scope of the invention.

As already described, a feature of my'invention resides `in theformation of aromatic hydrocarbons from acetylene at temperatures from600 to 1000 F. abovethose ordinarily employed,. and the advantages ofthis higher temperature operation have already been pointed out. I'arnlable to utilize such high aromatic-forming temperatures by operating inthepresence of hydrogen. Under such conditions, dehydrogenation ofacetylene with consequent carbon formation, and hydrogenation ofacetylene to ethane with consequent-low yieldsof desiredproduct issubstantially prevented, and higher and more etiicient conversions ofacetylene are obtained. Some` hydrogenation of acetylene to ethylene mayoccur', but if' se, it is in no way disadvantageou's'. The Ytemperatureconditions are chosen such that partial hydrogenation to ethylene ispossible and favorable, but at which total hydrogenation of acetylenetoethane or of any ethylene to ethane, is not promoted. The' contact timeis so chosentha't dehydrogenation of acetylene, and polymerization ofacetylene is kept at a minimum, and so chosen that unsaturates such asbutadiene, cyclopentadiene, and C6 dienes are formedV together with highyields of light aromatic hydrocarbons particularly, benzene and toluene.Only minor amounts of heavier aromatic components, tars and the like areformed at these selected temperatures and contact times. Typical ofpreferred ti'r're-temprat're relationships employed' in theprcticeofthe'a'ro'rnatics-forming step of action takingiplace in thearomatics-forming step. However, it is possible that (1) acetylene isfirst partiallyV hydrogenated to ethylene as indicatedby the-equation 11 (2) ethylene and acetylene thenrcopolymerize, to form butadiene asindicated by the equation and (3), butadiene thus formed copolymerizeswith ethylene or acetylene followed by dehydrogenatlon and cyclizationto benzene, as indicated by the following equation In any case, somehydrogenation of acetylene to ethylene undoubtedly takes place under theconditions of my process and possibly contributes to the high yields ofbenzene by virtue of its reaction with butadiene. Furthermore, thepresence of any ethylene formed has a stabilizing effect upon thereactant gases and may contribute to maintaining the low carbon yieldsobtained.

The amount of hydrogen present in the aromaticsforming step is importantin that it is advantageous that at least 40 percent of the gas in thearomatics-forming step consists of hydrogen. Usually the amount ofhydrogen produced in the acetylene-forming step is more than that neededto supply the necessary hydrogen to the aromatics-forming step, and nohydrogen from any other source is required.

Any gaseous hydrocarbon stock may be employed in the practice of myinvention for conversion to acetylene. The process has a distinctadvantage, in that methane, or a methane-rich gas such as conventionaldry natural gas, can be economically converted. The resultingacetylenerich product is satisfactory in any case for use in thearomatic-forming step. Lower temperatures may be required for conversionof the heavier hydrocarbons to acetylene, but usually the conditions ofthe aromaticforming step are substantially unchanged. y

My invention is illustrated by the following example. The reactants,their proportions, and other specific ingredients are presented as beingtypical and should not be construed to limit the invention unduly.

Example Natural gas of the following composition:

Component: Volume percent CH., 92 CZHS 4 C3H8 1 N2 3 is passed into thegas heating chamber of a pebble heater apparatus at a rate of 2040standard cubic feet per hour and heated therein to 2000 F. for a contacttime of 0.3 second at a pressure of 4 p. s. i. g. Under such conditionsof preheating, about 20 percent cracking takes place. The composition ofheated natural gas passed from the pebble heater chamber isapproximately as follows:

1Carbon and tar-free bases.

Simultaneously, a hydrogen-rich recycle gas of about 85 percent hydrogenpurity, is passed from a purification step discussed hereafter at a rateof 3420 standard cubic feet per hour, based on hydrogen, into a waterjacketed burner in admixture with commercial grade oxygen introduced atthe rate of 1710 standard cubic feet per hour, and the resultingadmixture burned. The ame resulting from this burning is formed at atemperature of about' 5000 F., and is ydirected axially into acylindrical elongated combustion chamber, attached to the burner toaxial- ,ly receive combustion gas therefrom. Steam is tangentiallyintroduced into the cylindrical elongated combustion chamber, in adirection perpendicular to the longitudinal axis of the combustionchamber, at a rate of 210 pounds ,per hour through ltwo conduit inletsnear the burner end of the combustionvchamber, disposed about 180 apart.Steam thus added, absorbs heat from the hot combusnon gas and tempers itto about 4000 F. The tangentially added steam follows an initial inwardspiral path and then flows helically downstream through the combustionchamber adjacent the chamber inner wall, imparting a swirling motion tothe axially owing combustion gas as it travels through the combustionchamber. Etiluent heated hydro- .carbon gas from the gas heating chamberof the pebble ,heater apparatus is passed radially into the swirlingtempered combustion gas mixture. A resulting natural gascombustion gasadmixture is formed at about 3000 F. and is passed into the mixingthroat of a Venturi tube having a longitudinal axis eleven inches inlength and a total angle of 21 degrees. The constricted-most portion ofthe Venturi tube has a diameter of two inches; the exit throat has atotal angle of 7 degrees and has a longitudinal axis 33 inches inlength. Hydrocarbon-combus- Vtion gas admixture is passed from theVenturi tube mixing throat through the constricted-most portion of theVenturi tube at an accelerated linear Velocity, and thereby quickly andcompletely mixed. The 33 inch Venturi tube exit throat is of suflcientlength to provide for the contact time required for pyrolysis of thehydrocarbon gas at 3000 F. to acetylene-rich product, which in thiscase, is

p 0.01 second. The approximate composition of the pyrolysis product, ona steam, carbon and tar-free basis, is as Acetylene-containing productis passed from the Venturi tube exit throat, and quickly quenched withsteam to terminate the reaction and prevent further reaction toundesirable products, particularly tar, carbon, hydrogen, and polymer.This is done by diverting the direction of Vflow of the eluent productgas simultaneously injecting quench steam at the rate of 613 pounds perhour into the product gas at the 90 turn in a longitudinal directiondownstream and passing the quenched product mixture into the mixingthroat of a second Venturi tube, having a longitudinal axis of 9 inchesand a total angle of 24 degrees. The diameter of the constricted-mostportion of this Venturi tube is 4 inches; the exit throat has alongitudinal axis of 16 inches in length, and a total angle of 8degrees. The quenched mixture in the Venturi tube mixing throat ispassed on through the constricted-most portion of the Venturi tube at anaccelerated linear velocity, and on through the exit throat. Quenchedproduct gas is passed from the second Venturi tube at a temperature of2100 F. into an auxiliary reaction chamber wherein the quench gasmixture is maintained at its existing temperature for a contact time for0.8 second. Under such conditions, the acetylene-containing gas isconverted to a crude aromatic hydrocarbon-containing product obtained ina yield of 1.0 gallon per MSCF of natural gas charged to the pebbleheater, containing about 70 percent benzene, and 10 percent toluene,with the remaining product comprising cyclopentadiene and other.dioleiins in the C4 to C6 range together with other light aromaticssuch as xylenes, styrene and methyl styrene, and relatively minoramounts of heavier aromatics, predominantly naphthalene and anthracene.

The hydrogen-rich recycle stream referred to hereinabove is recoveredfrom the product mixture in the auxiliary recovery equipment and isrecycled to the burning step above described. This hydrogen-rich recyclegas has the following approximate composition.

Natural gas is burned in place of hydrogen at the rate of 855 C. F. H.during non-process periods, or when starting up.

As will be evident, to those skilled in the art, various modications ofthis invention can be made, or followed, in the light of the foregoingdisclosure and discussion, without departing from the spirit or scope ofthe disclosure or from the scope of the claims.

I claim:

l. A process for the pyrolysis of a hydrocarbon to produce pyrolysisproducts including acetylene which process comprises burning hydrogenwith oxygen to form a combustion gas having a temperature in the range4500 Vto 5300 F., passing said combustion gas in a longitudinaldirection of ow, maintaining a helically moving blanket of tempering gasannularly disposed about the said longitudinally owing combustion gas insucient amount to cool said combustion gas to a temperature not higherthan 4200 F., preheating a gaseous hydrocarbon to a temperature in therange 1800 to 2400 F., introducing thus preheated gaseous hydrocarboninto admixture with said combustion gas in a generally transversedirection thereto, whereby mixing of combustion gas and gaseoushydrocarbon is eiected and said hydrocarbon is heated to a pyrolysistemperature in the range 2400 to 3500F., increasing the linear velocityof the resulting mixture to a value in the range 200 to 500 feet persecond, substantially decreasing said velocity and maintaining saidmixture in a high state of turbulence for a time in the range 0.001 to0.05 second, introducing a quenching iluid into said mixture to quenchsaid mixture below pyrolysis temperature and simultaneously abruptly andsharply changing the direction of ow of said mixture, increasing thelinear velocity of the quenched mixture while maintaining the quenchedmixture in a high state of turbulence, and recovering pyrolysis productsfrom the quenched mixture.

2. A process according to claim 1 wherein said combustion gas producedby said burning of hydrogen has a temperature in the range 5000 to 5300F.

3. A process for the pyrolysis of hydrocarbons to produce ethylene andacetylene, comprising burning hydrogen with oxygen to form combustiongas at a temperature of from about 5000 F. to about 5300 F., maintainingcombustion gas thus formed in a longitudinal direction of flow,maintaining a helically moving blanket of tempering gas annularlydisposed about said longitudinally owing combustion gas in an amount toabsorb heat from said combustion gas and cool same to a temperature nothigher than 4200 F., said helically moving tempering gas imparting aswirling motion to said cornbustion gas, preheating gaseous hydrocarbonto a temperature in the range of from 1800 to 2400 F., introducing thegaseous hydrocarbon thus preheated into admixture with swirlinglongitudinally moving combustion gas in a radial direction with respectto the longitudinal ow of said combustion gas whereby mixing ofcombustion gas and gaseous hydrocarbon is initiated and heat istransferred from said combustion gas to said hydrocarbon to heat same toa temperature in the range of 2400 to 3500 F., increasing the linearvelocity of the resulting tempering gas-hydrocarbon-combustion gasadmixture to a value in the range 200 to y500 feet per second, thendecreasing said velocity and maintaining ,said admixture in a high stateof turbulence for a contact time within the range offrom 0.001l Ito 0.05second, whereby acetylene and ethylene-containing hydrocarbon pyrolysisproduct is formed, introducing quenching uid in a predetermined amountinto said pyrolysis product to quench same to a temperature below about500 F. and abruptly changing the direction of ow of same through about aright angle, increasing the linear velocity of the resulting pyrolysisproduct-quenching fluid admixture and then maintaining same in a highstate of turbulence whereby quenching'of pyrolysis product is completedand a predetermined uniform temperature level is provided, passingquenched pyrolysis product to a product separation means and thereinseparating ethylene and acetylene, and recovering said ethylene andacetylene as products of the process.

4. A process for the pyrolysis of hydrocarbons to produce ethylene andacetylene, comprising burning hydrogen with oxygen of at least percentoxygen purity to form combustion gas at a temperature of about 5000 F.,maintaining combustionk gas thus formed in a longitudinal direction ofHow, maintaining a helically moving blanket of tempering gas annularlydisposed about said longitudinally flowing combustion gas in an amountto absorb heat from said combustion gas and cool same to a 4temperaturenot higher than 4200 F., said helically moving tempering gas imparting aswirling motion to said combustion gas, preheating gaseous hydrocarbonto a temperature in the range of from 1800 to 2400 F., introducing thegaseous hydrocarbon thus preheated into admixture with swirlinglongitudinally moving combustion gas in a radial direction with respectto the longitudinal ow of said combustion gas whereby mixing ofcombustion gas and gaseous hydrocarbon is initiated and heat istransferred from said combustion gas to said hydrocarbon to heat same toa temperature in the range of 2400 to 3500 F., increasing the linearvelocity of the resulting tempering gas-hydrocarbon-combustion gasadmixture to a value in the range 200 to 500 feet per second, thendecreasing said velocity and maintaining said admixture in a high stateof turbulence Yfor a contact time within the range of from 0.001 to 0.05second, whereby acetylene and ethylene-containing hydrocarbon pyrolysisproduct is formed, introducing quenching uid in a predetermined amountinto said pyrolysis product to quench same to a temperature below about500 F. and abruptly changing the direction of flow of same through anangle of 90 degrees, increasing the linear velocity of the resultingpyrolysis product-quenching iluid admixture and then maintaining same ina high state of turbulence whereby quenching of pyrolysis product iscompleted and a pre determined uniform temperature level is provided,passing quenched pyrolysis product to a product separation means andtherein separating ethylene and acetylene, and recovering said ethyleneand acetylene as products of the process.

5. A process for the pyrolysis of hydrocarbons, comprising burninghydrogen with oxygen of at least 90 percent oxygen purity to formcombustion gas at a temperature of about 5000 F., maintaining combustiongas thus formed in a longitudinal direction of ow, maintaining ahelically moving blanket of tempering gas annularly disposed about saidlongitudinally flowing combustion gas in an amount to absorb heat fromsaid cornbustion gas and cool same to a temperature not higher than 4200F., said helically moving tempering gas imparting a swirling motion tosaid combustion gas, preheating gaseous hydrocarbon to a temperature inthe range of from 1800 to 2400 F., introducing gaseous hydrocarbon thusheated into admixture with swirling longitudinally moving combustion gasin a radial direction with respect to the longitudinal flow of saidcombustion gas whereby intimate and rapid mixing of combustion gas andgaseous hydrocarbon is initiated and heat is transferred from saidcombustion gas to said hydroassen-1.3

`carbon to heat same to a tempera-ture in the range of 2400 to 3500 F.,increasing the linear velocity of the resulting temperinggas-hydrocarbon-combustion gas admixture to a value in the range to 200to 500 feet per second, then decreasing said velocity and maintainingsaid admixture in a high state of turbulence for a contact time withinthe range of from 0.001 to 0.05 second, whereby acetylene-containinghydrocarbon pyrolysis product is formed, diverting the direction of flowof said pyrolysis product at an angle of about 90, introducing quenchinguid in a predetermined amount longitudinally into saidacetylene-containing product when in diverted flow, again increasing thelinear velocity f the resuiting admixture of pyrolysis product andquench fluid to a value in the range of 200 to 500 feet per second, thendecreasing said velocity and maintaining the admixture in a high stateof -turbulence whereby quenching of pyrolysis product is completed and apredetermined uniform temperature level is provided, maintaining thequenched product mixture at a temperature within the range of 1800 to2300 F. for a contact time of 0.05 to 5.0 seconds, whereby aromatichydrocarbons and unsaturated aliphatic hydrocarbons are formed asproduct, separating said product into selected hydrocarbon fractions,and recovering said fractions.

6. The process of claim wherein said tempering gas is steam.

7. The process of claim 5 wherein said tempering gas is hydrogen.

8. Hydrocarbon conversion apparatus comprising, in combination: agenerally cylindrical combustion chamber; burner means positioned in oneend of said combustion chamber and in open communication therewith;inlet means in open communication with said combustion chamber andpositioned substantially tangentially with respect to the inner surfaceof said combustion chamber and adjacent said burner means; conduit meansin open communication with said combustion chamber 'at the end thereofopposite said burner means; inlet means in open communication with saidconduit means at an intermediate part thereof; a Venturi tube in opencommunication with said conduit means at the end thereof opposite saidchamber, said Venturi tube being substantially coaxial with saidconduit; another Venturi tube in open communication with thefirst-mentioned Venturi tube, the axes of the two Venturi tubes beingnoncoaxially and angularly disposed with respect to each other; inletmeans intermedi- Yate the two lVenturi tubes and generally coaxiallypositioned with respect to the second-mentioned Venturi tube; and outletmeans in open communication with the secondmentioned Venturi tube.

9. Apparatus for pyrolysis of hydrocarbons, comprising, in combination,burner means for burning hydrogen with oxygen, a iirst substantiallyunobstructed cylindrical elongated refractory section connected at oneend with said burner means to axially receivehot combustion gas fromburning therein, a second cylindrical elongated section open at bothends and having a smaller diameter than said first cylindrical sectionand co-axially connected to said iirst section opposite the burner end,fluid inlet means opening into said iirst section through its Vside wallnear the burner end and disposed to admit fluid in a direction tangentto the inner side wall of said first section and perpendicular to itslongitudinal axis, hydrocarbon inlet means opening radially into saidsecond cylindrical section, a first refractory Venturi tube co-axiallyconnected at its upstream end to said second section, ia secondrefractory Venturi tube in open communication at its upstream end Withthe downsream end of said iirst Venturi tube and having its longitudinalaxis disposed at a right angle to the longitudinal axis of Said firstVenturi tube, quench tiuid inletvmeans opening through the side wallintermediate said first and second Venturi tubes and axiallydisposedwith respect to said second Venturi tube, an auxiliary'reactionsection connected to the downstream end of said second Venturi tube andpositioned at right angles thereto, outlet means positioned intermediatesaid second Venturi tube and said auxiliary reaction section, and outletmeans in said auxiliary reaction section.

10. The apparatus of claim 9 in which the angle of the exit throat ofsaid second Venturi tube is about one-half the angle of the inlet throatthereof and the length of the outlet throat of said second Venuri tubeis about twice the length of the inlet throat thereof.

1l. The apparatus of claim 9 in which the length of the exit throat ofsaid rst Venturi tube is about three times the length of the inletthroat thereof.

References Cited in the le of this patent UNITED STATES PATENTS2,374,518 Wolk et al. Apr. 24, 1945 2,608,594 Robinson Aug. 26, 19522,750,420 Hepp June 12, 1956 2,750,434 Krejci .Tune 12, 1956 IUJ Se@EPARTMENT OF COMMERCE PATENT oFFCF,

CERTIFlCATE 0F @ERECTION Patent No; 382352,43 Fehmariy n., 195e Sem PRobinson.

It is hereby certified that error' appears in the printed specificationof the above numbered patent requiring correction and that. the said Letsers Patent. should read as corrected below.

Column Z line l0, after "tem= insert eeperatufcey manbainng the heatedgas at that temperaturen@ column 6;, line 5()y after "turbulence" inserteenecesserge; line' 62 strike' out "about twice the length of thelongitudinal exisn and. insert instead of Venturi Atube 69 may be aboulSigned end sealed this 6th day of Mey 19580 (SEAL) Atest:

KARL H., AXLINE ROBERT C. WATSON Attesting Officer Comnssioner ofPatents

1. A PROCESS FOR THE PYROLYSIS OF A HYDROCARBON TO PRODUCE PYROLYSISPRODUCTS INCLUDING ACETYLENE WHICH PROCESS COMPRISES BURNING HYDROGENWITH OXYGEN TO FORM A COMBUSTION GAS HAVING A TEMPERATURE IN THE RANGE4500 TO 5300*F., PASSING SAID COMBUSTION GAS IN A LONGITUDINAL DIRECTIONOF FLOW, MAINTAINING A HELICALLY MOVING BLANKET OF TEMPERING GASANNULARLY DISPOSED ABOUT THE SAID LONGITUDINALLY FLOWING COMBUSTION GASIN SUFFICIENT AMOUNT TO COOL SAID COMBUSTION GAS TO A TEMPERATURE NOTHIGHER THAN 4200*F., PREHEATING A GASEOUS HYDROCARBON TO A TEMPERATUREIN THE RANGE 1800 TO 2400*F., INTRODUCING THUS PREHEATED GASEOUSHYDROCARBON INTO ADMIXTURE WITH SAID COMBUSTION GAS IN A GENERALLYTRANSVERSE DIRECTION THERETO, WHEREBY MIXING OF COMBUSTION GAS ANDGASEOUS HYDRO-
 8. HYDROCARBON CONVERSION APPARATUS COMPRISING, INCOMBINATION: A GENERALLY CYLINDRICAL COMBUSTION CHAMBER, BURNER MEANSPOSITIONED IN ONE END OF SAID COMBUSTION CHAMBER AND IN OPENCOMMUNICATION THEREWITH, INLET MEANS IN OPEN COMMUNICATION WITH SAIDCOMBUSTION CHAMBER AND POSITIONED SUBSTANTIALLY TANGENTIALLY WITHRESPECT TO THE INNER SURFACE OF SAID COMBUSTION CHAMBER AND ADJACENTSAID BURNER MEANS, CONDUIT MEANS IN OPEN COMMUNICATION WITH SAIDCOMBUSTION CHAMBER AT THE END THEREOF OPPOSITE SAID BURNER MEANS, INLETMEANS IN OPEN COMMUNICATION WITH SAID CONDUIT MEANS AT AN INTERMEDIATEPART THEREOF, A VENTURI TUBE IN OPEN COMMNICATION WITH SAID CONDUITMEANS AT THE END THEREOF OPPOSITE SAID CHAMBER, SAID VENTURI TUBE BEINGSUBSTANTIALLY COAXIAL WITH SAID CONDUIT, ANOTHER VENTURI TUBE IN OPENCOMMUNICATION WITH THE FIRST-MENTIONED VENTURI TUBE, THE AXES OF THE TWOVENTURI TUBES BEING NONCOAXIALLY AND ANGULARLY DISPOSED WITH RESPECT TOEACH OTHER, INLET MEANS INTERMEDIATE THE TWO VENTURI TUBES AND GENERALLYCOAXIALLY POSITIONED WITH RESPECT TO THE SECOND-MENTIONED VENTURI TUBE,AND OUTLET MEANS IN OPEN COMMUNICATION WITH THE SECONDMENTIONED VENTURITUBE.